One Hundred Years of Fusion

Monday

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When I was a child I heard that practicable fusion power was thirty years in the future. That was more than thirty years ago, and it is not uncommon to hear that practicable fusion power is still thirty years in the future. Jokes have been made both about fusion and artificial intelligence that both will remain perpetually in the future, just out of reach of human technology — though the universe has been running on gravitational confinement fusion since the first stars lighted up at the beginning of the stelliferous era.

It is difficult to imagine anything more redolent of failed futurism than domed cities. Everyone, I think, will recall the domed city in the film Logan’s Run, which embodied so many paradigms of early 1970s futurism.

It would be easy to be nonchalantly cynical about nuclear fusion given past promises. After all, the first successful experiments with a tokamak reactor at the Kurchatov Institute in 1968 date to the time of many other failed futurisms that have since become stock figures of fun — the flying car, the jetpack, the domed city, and so on. One could dismiss nuclear fusion in the same spirit, but this would be a mistake. The long, hard road to nuclear fusion as an energy resource will have long-term consequences for our industrial-technological civilization.

Russian T1 Tokamak at the Kurchatov Institute in Moscow.

Like hypersonic flight, practicable fusion power has turned out to be a surprisingly difficult engineering challenge. Fusion research began in the 1920s with British physicist Francis William Aston, who discovered that four hydrogen atoms weigh more than one helium (He-4) atom, which means that fusing four hydrogen atoms together would result in the release of energy. The first practical fusion devices (including fusion explosives) were constructed in the 1950s, including several Z-pinch devices, stellarators, and tokamaks at the Kuchatov Institute.

Ever since these initial successes in achieving fusion, fusion scientists have been trying to achieve breakeven or better, i.e., producing more power from the reaction than was consumed in making the reaction. It’s been a long, hard slog. If we start seeing fusion breakeven in the next decade, this will be a hundred years after the first research suggested the possibility of fusion as an energy resource. In other words, fusion power generation has been a technology in development for about a hundred years. For anyone who supposes that our civilization is too short-sighted to take on large multi-generational projects, the effort to master nuclear fusion stands as a reminder of what is possible when the stakes are sufficiently high.

The Z machine at Sandia National Laboratory.

I characterized fusion as a “technology of nature” in Fusion and Consciousness, though the mechanism by which nature achieves fusion — gravitational confinement — is not practical for human technology. Mostly following news stories I previously wrote about fusion in Fusion Milestone Passed at US Lab, High Energy Electron Confinement in a Magnetic Cusp, One Giant Leap for Mankind, and Why we don’t need a fusion powered rocket.

There was a good article in Nature earlier this year, Plasma physics: The fusion upstarts, which focused on some of the smaller research teams vying to make fusion reactors into practical power sources. Here are some of the approaches now being pursued and have been reported in the popular press:

● High Beta Fusion Reactor The legendary Skunkworks, which built the U-2 and SR-71 spy planes, is working on a fusion reactor that it hopes will be sufficiently compact that it can be hauled on the back of a truck, and will produce 100 MW. (cf. Nuclear Fusion in Five Years?)

● magnetized liner inertial fusion (MagLIF) This is a “Z pinch” design that was among the first fusion device concepts, now being developed as the “Z Machine” at Sandia National Laboratory. (cf. America’s Underdog Fusion Experiment Is Closing In on the Nuclear Future)

● spheromak A University of Washington project formerly called a dynomak, a magnetic containment device in the form of a sphere instead of the tokamak’s torus. (cf. Why nuclear fusion will soon become reality)

● Polywell The Polywell concept was developed by Robert Bussard of Bussard ramjet fame, based on fusor devices, which have been in use for some time. (cf. Low-Cost Fusion Project Steps Out of the Shadows and Looks for Money)

● Stellerator The stellarator is another early fusion idea based on magnetic confinement that fell out of favor after the tokamaks showed early promise, but which are not the focus of active research again. (cf. From tokamaks to stellarators)

This is in no sense a complete list. There is a good summary of the major approaches on Wikipedia at Fusion Power. I give this short list simply to give a sense of the diversity of technological responses to the engineering challenge of controlled nuclear fusion for electrical power generation.

Polywell Fusion Reactor

Even as ITER remains the behemoth of fusion projects, projected to cost fifty billion USD in spending by thirty-five national governments, the project is so large and is coming together so slowly that other technologies may well leap-frog the large-scale ITER approach and achieve breakeven before ITER and by different methods. The promise of practical energy generation from nuclear fusion is now so tantalizingly close that, despite the amount of money going into ITER and NIF, a range of other approaches are being pursued with far less funding but perhaps equal promise. Ultimately there may turn out to be an unexpected benefit to the difficulty of attaining sustainable fusion reactions. The sheer difficulty of the problem has produced an astonishing range of approaches, all of which have something to teach us about plasma physics.

Stellarator devices look like works of abstract art.

Nuclear fusion as an energy source for industrial-technological civilization is a perfect example of what I call the STEM cycle: science drives technology, technology drives industrial engineering, and industrial engineering creates near resources that allow science to be pursued at a larger scope and scale. In some cases the STEM cycle functions as a loosely-coupled structure of our world. The resources of advanced mathematics are necessary to the expression of physics in mathematicized form, but there may be no direct coupling of physics and mathematics, and the mathematics used in physics may have been available for generations. Pure science may suggest a number of technologies, many of which lie fallow, with no particular interest in them. One technology may eventually come into mass manufacture, but it may not be seen to have any initial impact on scientific research. All of these episodes seem de-coupled, and can only be understood as a loosely-coupled cycle when seen in the big picture over the long term.

In the case of nuclear fusion, the STEM cycle is more tightly coupled: fusion science must be consciously developed with an eye to its application in various fusion technologies. The many specific technologies developed on the basis of fusion science are tested with an eye to which can be practically scaled up by industrial engineering to build a workable fusion power generation facility. This process is so tightly coupled in ITER and NIF that the primary research facilities hold out the promise of someday producing marketable power generation. The experience of operating a large scale fusion reactor will doubtless have many lessons for fusion scientists, who will in turn apply the knowledge gained from this experience to their scientific work. The first large scale fusion generation facilities will eventually become research reactors as they are replaced by more efficient fusion reactors specifically adapted to the needs of electrical power generation. With each generation of reactors the science, technology, and engineering will be improved.

The vitality of fusion science today, as revealed in the remarkable diversity of approaches to fusion, constitutes a STEM cycle with many possible inputs and many possible outputs. Even as the fusion STEM cycle is tightly coupled as science immediately feeds into particular technologies, which are developed with the intention of scaling up to commercial engineering, the variety of technologies involved have connections throughout the industrial-technological economy. Most obviously, if high-temperature superconductors become available, this will be a great boost for magnetic confinement fusion. A breakthrough in laser technology would be a boost for inertial confinement fusion. The prolixity of approaches to fusion today means that any number of scientific discoveries of technological advances could have unanticipated benefits for fusion. And fusion itself, once it passes breakeven, will have applications throughout the economy, not limited to the generation of electrical power. Controlled nuclear fusion is a technology that has not experienced an exponential growth curve — at least, not yet — but this at once tightly-coupled and highly diverse STEM cycle certainly looks like a technology on the cusp of an exponential growth curve. And here even a modest exponent would make an enormous difference.

This is big science with a big payoff. Everyone knows that, in a world run by electricity, the first to market with a practical fusion reactor that is cost-competitive with conventional sources (read: fossil fuels) stands to make a fortune not only with the initial introduction of their technology, but also for the foreseeable future. The wealthy governments of the world, by sinking the majority of their fusion investment into ITER, are virtually guaranteeing that the private sector will have a piece of the action when one of these alternative approaches to fusion proves to be at least as efficient, if not more efficient, than the tokamak design.

But fusion isn’t only about energy, profits, and power plants. Fusion is also about a vision of the future that avoids what futurist Joseph Voros has called an “energy disciplined society.” As expressed in panegyric form in a recent paper on fusion:

“The human spirit, its will to explore, to always seek new frontiers, the next Everest, deeper ocean floors, the inner secrets of the atom: these are iconised [sic] into human consciousness by the deeds of Christopher Columbus, Edmund Hillary, Jacques Cousteau, and Albert Einstein. In the background of the ever-expanding universe, this boundless spirit will be curbed by a requirement to limit growth. That was never meant to be. That should never be so. Man should have an unlimited destiny. To reach for the moon, as he already has; then to colonize it for its resources. Likewise to reach for the planets. Ultimately — the stars. Man’s spirit must and will remain indomitable.”

NUCLEAR FUSION ENERGY — MANKIND’S GIANT STEP FORWARD, Sing Lee and Sor Heoh Saw

The race for market-ready fusion energy is a race to see who will power the future, i.e., who will control the resource that makes our industrial-technological civilization viable in the long term. Profits will also be measured over the long term. Moreover, the energy market is such that multiple technologies for fusion may vie with each other for decades as each seeks to produce higher efficiencies at lower cost. This competition will drive further innovation in the tightly-coupled STEM cycle of fusion research.

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Note added Wednesday 15 October 2014: Within a couple of days of writing the above, I happened upon two more articles on fusion in the popular press — another announcement from Lockheed, Lockheed says makes breakthrough on fusion energy project, and Cheaper Than Coal? Fusion Concept Aims to Bridge Energy Gap.

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